Quantum angular-momentum selection rules for absorption of twisted light by bound electrons (Conference Presentation)

Author(s):  
Andrei Afanasev
2018 ◽  
Vol 20 (2) ◽  
pp. 023032 ◽  
Author(s):  
Andrei Afanasev ◽  
Carl E Carlson ◽  
Christian T Schmiegelow ◽  
Jonas Schulz ◽  
Ferdinand Schmidt-Kaler ◽  
...  

2020 ◽  
Vol 95 (8) ◽  
pp. 085509
Author(s):  
Zhuoyuan Wang ◽  
Shi Yao Chong ◽  
Peihong Cheng ◽  
Peng An ◽  
Jian Qi Shen

Author(s):  
Benjamin J. McMorran ◽  
Amit Agrawal ◽  
Peter A. Ercius ◽  
Vincenzo Grillo ◽  
Andrew A. Herzing ◽  
...  

The surprising message of Allen et al. (Allen et al. 1992 Phys. Rev. A 45 , 8185 ( doi:10.1103/PhysRevA.45.8185 )) was that photons could possess orbital angular momentum in free space, which subsequently launched advancements in optical manipulation, microscopy, quantum optics, communications, many more fields. It has recently been shown that this result also applies to quantum mechanical wave functions describing massive particles (matter waves). This article discusses how electron wave functions can be imprinted with quantized phase vortices in analogous ways to twisted light, demonstrating that charged particles with non-zero rest mass can possess orbital angular momentum in free space. With Allen et al. as a bridge, connections are made between this recent work in electron vortex wave functions and much earlier works, extending a 175 year old tradition in matter wave vortices. This article is part of the themed issue ‘Optical orbital angular momentum’.


Author(s):  
Andrew Forbes

Optical modes that carry orbital angular momentum (OAM) are routinely produced external to the laser cavity and have found a variety of applications, thus increasing the demand for integrated solutions for their production. Yet such modes are notoriously difficult to produce from lasers due to the strict symmetry requirements for their creation, together with the need to break the degeneracy in helicity. Here, we review the progress made since 1992 in producing such twisted light modes directly at the source, from gas to solid-state lasers, bulk to integrated on-chip solutions, through to generic devices for on-demand OAM in both scalar and vector forms. This article is part of the themed issue ‘Optical orbital angular momentum’.


2016 ◽  
Vol 113 (48) ◽  
pp. 13648-13653 ◽  
Author(s):  
Mario Krenn ◽  
Johannes Handsteiner ◽  
Matthias Fink ◽  
Robert Fickler ◽  
Rupert Ursin ◽  
...  

Spatial modes of light can potentially carry a vast amount of information, making them promising candidates for both classical and quantum communication. However, the distribution of such modes over large distances remains difficult. Intermodal coupling complicates their use with common fibers, whereas free-space transmission is thought to be strongly influenced by atmospheric turbulence. Here, we show the transmission of orbital angular momentum modes of light over a distance of 143 km between two Canary Islands, which is 50× greater than the maximum distance achieved previously. As a demonstration of the transmission quality, we use superpositions of these modes to encode a short message. At the receiver, an artificial neural network is used for distinguishing between the different twisted light superpositions. The algorithm is able to identify different mode superpositions with an accuracy of more than 80% up to the third mode order and decode the transmitted message with an error rate of 8.33%. Using our data, we estimate that the distribution of orbital angular momentum entanglement over more than 100 km of free space is feasible. Moreover, the quality of our free-space link can be further improved by the use of state-of-the-art adaptive optics systems.


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